Loc: Long Beach, CA
J.I. Rodale's Synonym Finder rocks the house. Also, I recently picked up the Oxford American Dictionary and Thesarus combination, which I'm liking. It gives the synonym right under the definition. I have the large paperback version, but I think I might pick up the hardcover one for home.
I have a small paperback of Roget's Thesaurus at work. I hate it. It fails me every time.